1. Technical Field
The present invention relates in general to an assembly and method for bundling wires, and in particular to an improved assembly and method for encasing wires utilized within a head gimbal assembly of a DASD file. Still more particularly, the present invention relates to an improved assembly and method for automated encapsulation of a wire bundle utilized within a head gimbal assembly of a DASD file.
2. Description of the Related Art
Within magnetic disk storage devices, head gimbal assemblies (HGAs) are utilized to support a magnetic head over a magnetic disk. With reference now to FIG. 1A, there is illustrated a top plan view of a conventional HGA. As illustrated, HGA 10 includes arm 12, mount 14, and head 16. In general, mount 14 is rigidly fixed to a moving carriage within the access mechanism of the magnetic disk storage device. Arm 12 includes a proximate end which is secured to mount 14 and a distal end to which head 16 is attached. Arm 12 functions as a spring which enables head 16 to float above a magnetic disk (not illustrated). Electrical impulses transduced by head 16 from data stored on the magnetic disk are conducted to electronics (not illustrated) within the magnetic disk storage device by wires 20, which commonly comprise two sets of twisted-pair wire. As depicted, wires 20 are encased in tube 18, which in turn is secured to HGA 10 by clips 26. One end of tube 18 is secured to bracket 22 by interference fit into one of slots 24.
With reference now to FIG. 1B, there is depicted a cross sectional view of tube 18 which contains wires 20. As illustrated, along the length of wires 20 encased by tube 18, wires 20 are not held at a fixed relationship to each other, but simply lie within tube 18. Because wires 20 may move with respect to each other during the positioning of arm 12, portions of the twisted pair typically comprising wires 20 may become untwisted, creating inconsistent electrical characteristics along the length of wires 20 and increasing the mutual inductance between the twisted pair. In addition, movement of wires 20 within tube 18 increases the noise component of the signals conducted by wires 20, concomitantly decreasing the signal to noise ratio.
Tube 18 is utilized within HGA 10 for a variety of reasons. First, tube 18, which is typically formed of flexible plastic, provides a mechanical structure that may be secured to HGA 10 during assembly utilizing clips 26. In addition, tube 18 is easily secured to bracket 22 by interference fit. Finally, encasing wires 20 within tube 18 insures that wires 20 are protected and held in a safe position during subsequent steps of the assembly of the magnetic disk storage device.
To minimize assembly costs, manufacturers of magnetic disk storage devices, such as International Business Machines Corporation, have become interested in utilizing automated assembly lines to assemble HGAs. Although currently available sophisticated assembly line equipment can perform some steps of the assembly process such as automatically attaching wires 20 to arm 12 and head 16 to arm 12, other assembly steps cannot easily be performed by automated equipment. For example, it is difficult, if not impossible, for an automated assembly line to place a conventional tube 18 over wires 20 while HGA 10 is in process. Consequently, industry has heretofore relied on low-cost manual labor to assemble HGA 10 utilizing one of a variety of techniques. For example, with reference to FIG. 1A, one assembly method is as follows. A precut bundle of wire 20 is inserted into tube 18 at a facility separate from the HGA assembly plant. This wire and tube assembly is purchased and brought to the HGA assembly area. At the HGA assembly area, a worker attaches wires 20 to head 16 and places head 16 with wires 20 attached into a tool block. Arm 12 is attached to mount 14 and is also placed by the worker into the same tool block. The worker then affixes head 16 to arm 12 with a suitable adhesive. Finally, the worker attaches tube 18 to HGA 10 by crimping clips 26 around tube 18. Care must be taken by the worker to avoid damaging wires 20 while in the process of crimping clips 26. Because the foregoing assembly steps, and in particular the steps performed to insert wires 20 into tube 18 and to attach tube 18 to HGA 10 are time consuming as compared to an automated assembly process, the cost associated with manual labor has traditionally been a major component of HGA assembly cost.
Consequently, it would be desirable to provide a method and assembly which enable fully automated assembly of head gimbal assemblies within magnetic disk storage devices.